Safety control mechanism for liquid fuel burners



L. l. ALDRICH jan. 10, 1933.

Original Filed April 16, 1925 Patented Jan. 10, 1933 UNITED STATESPATENT OFFICE LOYJD I. ALDRICH, OF PEORIA, ILLINOIS,

PREFERRED OIL BURNERS, INCL, OF PEORI ASSIGNOR, BY MESNE ASSIGNMENTS, TO

A, ILLINOIS, A CORPORATION OF ILLINOIS SAFETY CONTROL MECHANISM FORLIQUID FUEL BURNERS Application filed April 16, 1923, Serial No.632,541.

The object of my invention is in the provision of a thermal safetycontrol mechanism mounted in a combustion chamber and cooperating with aconventional electrically operated fuel burning device in such mannerthat failure of combustion within said chamber during operation of theburner will result in a stopping of the action thereof.

Another object of my invention is in the provision of a thermal safetycontrol mecha nism adapted to make or break an electrical connectionupon its initial movement in either direction due to temperaturevariations.

A further object of my invention is in the provision of a specialthermal safety control device adapted upon initial movement of thethermal member thereof in either direction to make or break anelectrical circuit and to still be capable of further movement due toincreased or reduced temperature conditions without a correspondingeffect upon the contact portion of the device.

Other objects of my invention will appear in the following specificationin connection with the annexed drawing in which Figure l is a sideelevation of my thermal safety control device showing its mounting withrelation to a combustion chamber,

Figure 53 is an end elevation thereof.

Figure 3 is an enlarged side elevation showing in detail the contactportions of the device,

In the drawing in Figure l my thermal safety control device is shownmounted in connection with a combustion chamber 10 or rather a portionthereof. It might well be said at this time that my device is adapted tobe used in connection with any formal electrically controlled fuelburning device and inasmuch as this application is directed merely tothe safety control means therefor it is not thought necessary either toshow or go into any detailed description of said burner member. Theburner may include practically any type of fuel atomizer. Genorally itmay be said that an electric motor Renewed June 3, 193%..

controls the discharge of the fuel mixture in the combustion chamber.The present day burner is automatic in its control and has in thecombination which permits such automatic operation, a thermostat, aseries of electrical switches, an ignition means for the fuel blast, anda safety control mechanism,

this later portion forming the subject mat-- ter of the presentapplication.

Thermare various forms of safety control mechanism including, overflowcups co-operatlng with electrical switches controlling the burnermechanism, those having connection with the so-called pilot light orignition member which control the burner from the heat given therefrom,and again thermal safety control means, in which the operation of theburner is controlled by combustion conditions. I

In the present application, for the purpose of joining it with theformal burner device, it is thought sufiicient to say that it isincluded in the electrical circuit with said device and the series ofswitches controlling same including a so-called time switch,

My safety device is mounted as said before in either the wall of thecombustion chamber or in the door ll thereof, a portion of which 1 isshown in Figure 1. There has been no attempt to show the completecombustion chamber because the present device is adapted to be used inconnection with any form or type of chamber that is desired, A hollowtube is inserted thru an aperture in the door of the combustion chamberand is positioned therein positively by the lock nuts 13 and it threadedthereon, Keyed to the inner end id of the tube 12 is a support 16fashioned in such manner that its lower portion 1? is adapted to supportin a vertical manner the thermal or lei-metal strip 18. Attached to theupper end'of the thermal metal strip 18 is a longitudinally disposed rod19 slidably related to the hollow tube 12. ,Keyed to the outer end 20 ofsaid tube 12 the frame generally designated as 21, this portion be ingclearly shown in the detailed Figure 3 wherein the rollers 22 and 23 arepivoted in the upper portion as at 24 and 25 respective ly. Surroundingthe longitudinally disposed Mil rod 19 and slidable thereon is a saddlemember 26. A coil spring engages said saddle at 28 and is connected atits lower end to a split yoke or contact lever 29- pivoted to the frame21 as at 30. The coil spring 27 has a tensioned mounting with relationto the saddle and yoke member. At 31 and 32 are shown the opposed stopscrew and contact points having a gap there-between thru which the yokeor contact member 29 is adapted to oscillate. The stop screw 31 ispositively positioned with relation to the frame by means of lock nut33, and the contact point 32 is similarly locked by a nut 34, however,upon this side'the nut engages an insulation member 35 attached by meansof screws 36 to the block 21. A ground wire 37 is connected to the frameas at 38 and a second wire 39 is connected at 40 to the contact point 32completing the electrical circuit when the yoke is in engagementtherewith. The above electrical connections are in circuit with thevarious electrical controls and switches operating in conjunction withthe before-mentioned burning device.

The operation of my device is as follows: Having in mind the fact thatthe present safety control mechanism is used with a burning devicehaving electrical controls therefor, I will say that the present safetymeans is mounted as previously described with the thermal metalstrip-disposed within the combustion chamber in a position to beeffected by the heat from the ignited fuel discharge.

When the burner device is idle the safety control mechanism will be inthe position shown in full lines in Figure 1. Now upon the operation ofthe burner device and consequent iiame within the combustion chamber thethermal or bi-metal strip will be extended as shown in dotted lines inFigure 1 due to the raise in temperature. The inward movement of saidstrip will likewise draw the longitudinally disposed rod 19 outwardly toa similar extent. The movement of said rod will also result in movementof the saddle 26 tensioned thereon by the coil spring 27. The movementof the saddle likewise moves the coil spring which has connection at itslower end with the yoke 29 which movement subsequently withdraws saidyoke or lever from engagement with the contact point 32 to the dottedline position shown in Figure 1; or in other words, breaks the contact.The initial inward movement of the rod 19 as is clearly shown, resultsin a similar movement of the saddle. However, any movement of saidsaddle beyond the roller 22 is prevented and hence increased temperaturewill result in a further inward movement of the thermal stri andconsequent withdrawal of the rod 19, ut not of the saddle. In otherwords, the initial movement of the thermal strip breaks the electricalcircuit and said strip is still permitted to move as far as it will,

teasers this movement of course being controlled directly by the amountof heat in the combustion chamber. 9 When the operation of the burnerceases there is of course a consequent decrease in temperature with acorresponding outward movement of the thermal strip and rod 19. Theinitial inner movement of the rod carries with it the saddle 26 untilsaid saddle abuts the opposite roller 23. This move-' ment of the saddledue to the connection of the coil spring with the yoke 29 again permitssaid yoke to make contact with the point 32 and the safety controlmechanism is again in its normal position.

Perhaps it might be well to bring out the reason for the making of theelectrlcal contact upon the cessation ofburner activity. When the burnercommences its action there is an electrical circuit made, including thesafety device, some electrical switches and a so-called time switch.Should there be a failure of ignition of the fuel mixture dischargethere will of course be no increase of temperature within the combustionchamber to act upon the thermal strip. To prevent further activity ofthe burner which is discharging a continuous stream of unignited fuelmixture into the combustion chamber,-

the above mentioned electrical circuit including the safety device andthe time switch has the current passing therethru with the result thatsaid time switch within a determined period will be heated to such anextent that a contact-in the circuit will be broken, with a consequentstopping of the burner and cessation of fuel discharge. However, thenormal operation will result in the almost immediate breaking of theelectrical contact due to the movement of the thermal strip and hence,the cutting out of the time switch from the circuit so that the burneris free to operate.

As said before, l have not included in my showing all the abovementioned electrical switches, burner member, etc., because they aremerely formal and their operation has merely been described inconnection with my safety device for the purpose of more clearlybringing out the-action thereof.

What I claim is:

1. In a thermal safety control, in combination, relatively spacedcontact points, a suitably supported thermal metal strip, a contactmember, and means active to shift the contact member thru the deflectiveactivity of the thermal strip including, a shiftable member connectedwith the thermal strip, a sleeve loosely mounted on the shiftablemember, stop members adapted to limit the movement of the sleeve uponthe shiftable member, and means connecting the sleeve and the contactmember in a tensioning relation.

2. In a device of the class described, in combination, a thermal strip,contact points, a contact arm, connecting means between the thermalstrip and the contact member including, a shiftable member connectedwith the thermal strip, including a shiftable bar, a sleeve thereon, atensionmg member connecting the sleeve and contact member active undernormal conditions to efiect concurrent movement of the bar and sleeve,and stop members suitably disposed to limit the movement of the sleevemember under movement of the bar thru the activities of the thermalstrip beyond the reasonable requirement to eifect contacts.

3. In a device of the class described, in combination, a thermal strip,contact points a contact lever, a shiftable member controlle by theaction of the thermal strip, a sleeve thereon, means for holding thesleeve and contact lever in tensioned relation, and stop members adaptedto limit the movement of the sleeve member in either direction beyondits required limit for movement of the contact lever, but notrestricting the further movement of said shiftable member.

4. In a device of the class described, in combination, a thermal stripadapted to be disposed within a combustion chamber, contact points, acontact lever adapted to oscillate between said points, a shiftablemember controlled by the thermal metal strip and tensioned connectinmeans between the shiftable member and contact lever whereby the initialmovement of said shiftable member in either direction snaps said contactlever against one of said contact points without further movementthereof, due to the continued movement of said shiftable member.

5. In a device of the class described, in combination, a thermal metalstrip, contact points, a contact member adapted to oscillate betweensaid points, and means including a shiftable rod and connectingmechanism whereby the initial movement of said shiftable rod in eitherdirection controlled by the said thermal strip will result in' animmediate movement of the contact member without further disturbancethereof due to the continued movement of said shiftable member.

6. In a device of the class described, in combination, a thermal membersensitive to combustion conditions, a contact point and a stop membersuitably and adjustably distanced from one another, a contact membercooperating with said oint to make or break an electric circuit, anconnecting means between said thermal member and contact member wherebythe initial movement of said thermal member in either direction willimmediately snap said control member against either the contact point orsto to make or break the electrical circuit and t ereafter permitfurther movement of said thermal memger without movement of the contactmem- 7. The combination with an electric circuit including a switch, ofa thermostatic control for said switch includin a thermal member, andmeans for immediately actuatin the switch upon initial movement of the termal member in either direction comand closing the circuit comprisin alon tudinally movable member, a sli ing friction element bearing againstsaid member, said mechanism including spring operated means operativeimmediately upon the initial movement of the thermal member in eitherdirection to open and close the circuit, said means permitting continuedmovement of the thermal member without further actu ation of said means.

In testimony whereof he afiixes his signature.

LOYD I. ALDRICH.

